The parent application identified above discloses a film transport system in which an elongated control member, preferably a crank rod or for example a rack, is spring-driven in a first direction from a first to a second position when the user depresses the camera's release button, the rod triggering a shutter operation during its first-direction movement, or else performing some other camera function. Upon completion of the first-direction movement, the transport motor of the camera's film transport system becomes coupled to the rod and drives it in the opposite second direction back towards the first position, during which for example the rod resets the shutter and/or performs other functions. When the rod is returned by the motor to its original position, the rod becomes decoupled from the motor, so that the motor cannot counteract the force of the drive spring which drives the rod in its first direction.
In the system disclosed in that application, the rod is arrested in first position by a blocking or trigger lever, and to initiate an exposure the user depresses the camera's trigger or release button, causing such trigger lever to move to an unblocking position, permitting the rod to be driven in the first direction by the drive spring. If the user wishes to operate the camera in the sequential exposure mode, the user keeps the release button uninterruptedly depressed for as long as he wishes the exposure sequence to continue.
Most users, when wishing only a single exposure, will instinctively let go of the camera's trigger button and thereby reblock the control rod before the control rod can begin another first-direction spring-powered stroke, or else such users quickly learn and become confortable with the fact that they must do so. Other users, however, have the habit of persistently holding down the trigger button even when a single exposure is intended, and for these users such a technique for selecting between the single-exposure mode and the sequential-exposure mode is very troublesome.